This patent application claims priority based on a Japanese patent application, H11-067366 filed on Mar. 12, 1999, the contents of which are incorporated herein by reference.
1. Field of Invention
The present invention relates to a glass rod manufacturing method and a glass rod manufacturing apparatus that can manufacture a straight glass rod.
2. Description of Related Art
FIG. 1 shows a conventional glass base material first elongating apparatus 400. A glass base material 102, which is a base material of an optical fiber, is usually elongated by the glass base material first elongating apparatus 400. This reduces the diameter of the glass base material 102, to produce a glass rod 106. The glass rod 106 has a diameter from 3 mm to 5 mm larger than the most convenient diameter to draw an optical fiber. The most convenient diameter for drawing an optical fiber is 30 mm to 80 mm.
A glass base material first elongating apparatus 400 comprises a heating furnace 100 that heats the glass base material 102, a hanging mechanism 105 that supplies said glass base material 102 to the heating furnace 100, and a drawing chuck 104 that holds and elongates the heated glass base material 102. To elongate the glass base material 102, the glass base material first elongating apparatus 400 supplies the glass base material 102 to the heating furnace 100 using hanging mechanism 105. Here the glass base material 102 is heated to approximately 2000xc2x0 C. The first elongating apparatus 400 then holds the glass base material 102 by the drawing chuck 104, and draws the glass base material 102 from the heating furnace 100 downward continuously to form a glass rod 106.
FIG. 2 shows a configuration of a conventional glass lathe 110. The glass rod 106 made by the glass base material first elongating apparatus 400 undergoes secondary elongation by the glass lathe 110 to produce a preform 107. At this time, the diameter of the glass rod 106 is reduced to prescribed diameter. The glass lathe 110 comprises chucks 118 and 119 that hold the glass rod 106, a tail stock 116 which moves the chuck 119, and a heating source 122 which heats the glass rod 106. One side of the chuck 118 is fixed, and the other side of the chuck 119 movable. A traction force can be applied to the chuck 119. The glass rod 106, which is held by the chucks 118 and 119, is heated by the heating source 122. The heated glass rod 106 is elongated by moving the tail stock 116 which pulls the glass rod 106. The result is, the diameter of the glass rod 106 reduces to become the prescribed diameter
There was the possibility of manufacturing bent glass rods 106 when using a conventional glass base material first elongating apparatus 400 to elongate the glass base material 102. One of the causes of manufacture of bent glass is when the elongating axis of the glass base material first elongating apparatus 400, along which the glass base material 102 being elongated, are not vertical. Conventionally, the elongating axis of the glass base material first elongating apparatus 400 is adjusted by setting the plumb bob on the glass base material first elongating apparatus 400 and adjusting the elongating axis to be parallel to the string which is connected to the plumb bob. However, this method of using the plumb bob cannot adjust the axis which connects the hanging mechanism 105 and the drawing chuck 104 that actually hold the glass base material 102.
Also, when using a conventional glass lathe 110 to elongate the glass rod 106 to manufacture the preform 107 further problems often arose. These problems included variation in the diameter of the preform 107 because the amount of gas provided to the heating source 122 and the speed of moving the tail stock 116 differed for each preform 107 produced.
When elongating a bent glass rod 106, which is made by a conventional glass base material first elongating apparatus 400, to make a preform 107 by the glass lathe 110, the diameter of the preform 107 varied. When manufacturing optical fibers by drawing a preform 107 with a varying diameter, the diameter of the optical fibers produced also varies. This makes it difficult to manufacture an optical fiber of high quality.
As stated, it is an object of the present invention to provide a glass rod manufacturing method and a glass rod manufacturing apparatus that can solve the problems outlined above. The object of the present invention can be achieved by the combinations of features described in the independent claims of the present invention. The dependent claims define further advantageous embodiments of the present invention.
According to the first aspect of the present invention, a method for manufacturing a glass rod, which is a parent material of an optical fiber, can be provided such that said method comprises: adjusting a vertical inclination of a standard rod having a predetermined straightness; and heating and elongating a base material, which is a parent material of the glass rod, along an axis of the standard rod, the vertical inclination of which is adjusted, to generate the glass rod.
A method for manufacturing a glass rod can be provided such that the base material is elongated with a furnace which heats the base material, a hanging mechanism which supplies the base material to the furnace, and an elongating mechanism which pulls the base material heated by the furnace along the axis of the standard rod to produce the glass rod, and wherein the adjusting the vertical inclination includes: holding the standard rod by the hanging mechanism; and adjusting a vertical inclination of the standard rod held by the hanging mechanism to be a vertical direction.
A method for manufacturing a glass rod can be provided such that the adjusting the vertical inclination further includes: holding the standard rod by the elongating mechanism; and adjusting a vertical inclination of the standard rod held by the elongating mechanism to be a vertical direction.
A method for manufacturing a glass rod can be provided such that the adjusting the vertical inclination further includes: holding the standard rod by both of the hanging mechanism and the elongating mechanism; and adjusting a vertical inclination of the standard rod held by both of the hanging mechanism and the elongating mechanism to be a vertical direction.
A method for manufacturing a glass rod can be provided such that the base material is elongated with a furnace which heats the base material, a hanging mechanism which supplies the base material to the furnace, and an elongating mechanism which pulls the base material heated by the furnace along the axis of the standard rod to produce the glass rod, and wherein the adjusting the vertical inclination includes: holding the standard rod by the elongating mechanism; and adjusting a vertical inclination of the standard rod held by the elongating mechanism to be a vertical direction.
A method for manufacturing a glass rod can be provided such that the adjusting the vertical inclination further includes: holding the standard rod by the elongating mechanism; and adjusting a vertical inclination of the standard rod held by the hanging mechanism to be a vertical direction.
A method for manufacturing a glass rod can be provided such that the adjusting the vertical inclination further includes: holding the standard rod by both of the hanging mechanism and the elongating mechanism; and adjusting a vertical inclination of the standard rod held by both of the hanging mechanism and the elongating mechanism to be a vertical inclination.
A method for manufacturing a glass rod can be provided such that the base material is elongated with a furnace which heats the base material, a hanging mechanism which supplies the base material to the furnace, and an elongating mechanism which pulls the base material heated by the furnace along the axis of the standard rod to produce the glass rod, and wherein the adjusting the vertical inclination includes: holding the standard rod by both of the hanging mechanism and the elongating mechanism; and adjusting a vertical inclination of the standard rod held by both of the hanging mechanism and the elongating mechanism to be a vertical direction.
The elongating mechanism holds an approximate center of longitudinal direction of the standard rod during the adjusting the vertical inclination. The adjusting the vertical inclination of the standard rod held by both of the hanging mechanism and the elongating mechanism can be less than approximately 0.5 mm per 1 m length.
According to the second aspect of the present invention, an apparatus for manufacturing a glass rod, which is a parent material of an optical fiber, can be provided such that the apparatus comprises: a furnace which heats a base material, which is a parent material of the glass rod; a standard rod having a predetermined straightness; a hanging mechanism which supplies the base material to the furnace along an axis of the standard rod; and an elongating mechanism which pulls the base material heated by the furnace along the axis of the standard rod to produce the glass rod, wherein: at least one of the hanging mechanism and the elongating mechanism holds the standard rod to adjust a vertical inclination of the axis of the standard rod. The standard rod can be made of ceramic. The standard rod can have a length of the base material and dummy rods that are welded onto both ends of the base material.